On Wed, Jul 20, 2011 at 05:30:17PM +0200, Eric Dumazet wrote:

Le mercredi 20 juillet 2011 à 11:18 -0400, Neil Horman a écrit :

quoted

On Wed, Jul 20, 2011 at 06:24:15AM +0200, Eric Dumazet wrote:

quoted

Le mardi 19 juillet 2011 à 22:07 -0400, Neil Horman a écrit :

quoted

quoted

I think this is a good idea.  It lets pktgen dynamically make the clone/share
decision dynamically and only impacts performance for those systems.

Just let pktgen refuse to use clone_skb command for these devices.

copy that, This is by no means final, but what do you think of this?  If its
agreeable to you, Ben, et al. I can add this to my local tree and start auditing
all the drivers that may need to have the flag set.

Regards
Neil

diff --git a/include/linux/if.h b/include/linux/if.h
index 3bc63e6..ae904fe 100644
--- a/include/linux/if.h
+++ b/include/linux/if.h

@@ -76,6 +76,7 @@
 #define IFF_BRIDGE_PORT	0x4000		/* device used as bridge port */
 #define IFF_OVS_DATAPATH	0x8000	/* device used as Open vSwitch
 					 * datapath port */
+#define IFF_CANT_SHARE_SKB	0x10000	/* Device can't share skbs in tx path */
 
 #define IF_GET_IFACE	0x0001		/* for querying only */
 #define IF_GET_PROTO	0x0002

diff --git a/net/core/pktgen.c b/net/core/pktgen.c
index f76079c..bf6d88d 100644
--- a/net/core/pktgen.c
+++ b/net/core/pktgen.c

@@ -1071,6 +1071,9 @@ static ssize_t pktgen_if_write(struct file *file,
 		if (len < 0)
 			return len;
 
+		if (pkt_dev->priv_flags & IFF_CANT_SHARE_SKB)
+			return -EOPNOTSUPP;
+

Well, the general idea was to intercept the "clone_skb XXX" command and
cap XXX to 0 for said devices.

Isn't that exactly what this does?  Disallows a user from issuing the cone_skb
command in a pktgen script if the underlying driver can't support the sharing of
skbs.

So some admin can still use pktgen without clone_skb stuff.

Yes. this doesn't preclude that unless you see something I dont
Neil